Optical coherence tomography (OCT) uses Michelson Interferometer and low coherence light source. Ideally, the light beam is split into two paths, a reference arm path and a sample arm path, by a beam splitter (BS). Light on the reference arm path is reflected by a planar mirror and a part of the reflected light from the planar mirror passes through the beam splitter and is incident onto a photodetector (PD). Light on the sample arm path is reflected by the test sample, and a part of the reflected light from the test sample is reflected by the beam splitter and is incident onto the photodetector. If light on the reference arm path and light on the sample arm path has overlap in coherence length, then they are interfered. The interference signal may be measured by the photodetector. The optical path difference (OPD) between the reference arm path and the sample arm path may be changed by moving the planar mirror forward and backward, to generate interference information of the test sample on different depth. The interference information may be further analyzed to obtain information of the test sample.
Full-field optical coherence tomography (FFOCT) is developed from a Time-domain OCT, which improved scanning and image capture of the traditional time-domain OCT to improve the scan speed.